A. Field of the Invention
The present invention relates to a one-piece closed-shape structure and a method for manufacturing a one-piece closed-shape structure. In particular, the present invention relates to a one-piece fuselage and a method for manufacturing a one-piece fuselage.
B. Background of the Invention
Since the 1940""s and 1950""s, aircraft have been manufactured from lightweight metals, primarily aluminum. More recently, composite materials (such as fiber reinforced plastics) have been used to manufacture some aircraft. The manufacture of such aircraft include the manufacture of the fuselage (the central body of the aircraft), the wings, and the various other components of the aircraft.
In the manufacture of an aircraft fuselage with metals or composites, the typical manufacturing process involves the combination of several pieces that are individually manufactured and then bonded together to form the fuselage. These multiple steps have many disadvantages, including both high cost and significant time.
The creation of a single-piece fuselage would provide many advantages over fuselages manufactured from the combination of multiple parts. These advantages potentially include lower cost, lighter weight, improved integration, safety, improved performance, noise reduction, improved aerodynamics, and styling flexibility.
As for lower cost, a one-piece fuselage is less costly to fabricate, because there is only one part to manufacture, and there are no fasteners. Thus, the one-piece design saves money in both the fabrication stage and in combination stage. In addition, the work areas needed at a manufacturing facility are less for a one-piece design, because multiple parts require dramatically more workspace areas.
As for lighter weight, because there are fewer parts to a one-piece fuselage, and because there are fewer fasteners, a one-piece fuselage is lighter than a fuselage created from multiple parts. The lighter the aircraft, the more carrying capacity that the aircraft will have, which is a substantial benefit.
As for improved integration, a one-piece fuselage is easier to integrate with the other components of the aircraft, such as the tail cone, the wings, and the other parts of the aircraft. Additionally, the interior of a one-piece fuselage would also be easier to integrate, because there is only one form that must be properly fitted. Moreover, problems with integration of multiple parts (such as dimension variation and other fabrication problems) would be completely eliminated in a one-piece design.
As for safety, a one-piece fuselage offers structural advantages over a fuselage fabricated from multiple parts. In the initial fabrication of the one-piece fuselage, the structure may be designed with safety improvements (such as strengthened areas, etc.). Additionally, because the one-piece fuselage does not have most of the fasteners necessary for combining the multiple parts, the one-piece design is more structurally sound, which provides increased passenger safety. Also, a one-piece fuselage is more crashworthy. A one-piece fuselage provides the advantages of an integrated structure, which has numerous crashworthiness benefits.
As for improved performance, there are both objective and subjective improvements. For objective improvements, there is of course the improved aerodynamics, which results in greater speed. For subjective improvement, there is the noise reduction, which results in a more comfortable ride. In some way, all of the advantages of the one-piece fuselage play a role in improved performance.
As for noise reduction, because a one-piece fuselage would result in improved aerodynamics, a further benefit would be a diminution of air disruption, which results in noise reduction. Any increase in the smoothness of an aircraft has the benefit of noise reduction. Thus, to the extent that the creation of a one-piece fuselage results in the improvement of aerodynamics, there is a reciprocal decrease in noise.
As for improved aerodynamics, a one-piece fuselage inherently is more aerodynamic than a fuselage created from the combination of multiple parts. This improvement in aerodynamics would result from the absence of seams or joints as well as the absence of rivets or other external fasteners. In modern aircraft, seams and joints between the combined parts increase drag and thus diminish aerodynamics. By omitting the seams and joints in a one-piece fuselage, aerodynamics would be improved. Also, in modern aircraft, the external fasteners for flanges and other structure internal to the fuselage also increase drag and diminish aerodynamics. A one-piece fuselage would omit most fasteners and would thus improve aerodynamics.
As for styling flexibility, the capability to create a one-piece fuselage would provide more opportunities for aircraft design. Because multiple parts are not combined to create the fuselage, unique shapes may be possible, that were previously difficult to achieve. By improving the design and styling of the aircraft with a one-piece fuselage, it would thus be possible to create a more attractive aircraft for the market.
Therefore, it is desirable to provide a one-piece fuselage.
For a one-piece fuselage, either metal or composite materials may be used. Metal has more disadvantages, due to the inability to fabricate all components of the fuselage in a single step. Composite materials are thus more advantageous for the fabrication of a one-piece fuselage, because composite materials may be fabricated simultaneously.
Therefore, it is further desirable to provide a one-piece fuselage manufactured from composite materials.
Methods and structures in accordance with the invention provide for a one-piece structure manufactured from composite materials, including a one-piece fuselage. One embodiment includes manufacturing a one-piece fuselage by filament winding. Other embodiments for manufacturing a one-piece fuselage may also be used.
Methods and structures consistent with the present invention may overcome the shortcomings of conventional systems by providing a one-piece closed shape structure manufactured by composite materials. Additional objects and advantages of the invention will be set forth in part in the description, which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects of the invention will be realized and attained by means of the elements and combination particularly pointed out in the appended claims.
In accordance with an embodiment of the present invention, a method of manufacturing a one-piece closed-shape structure using a mandrel comprises: preparing the mandrel, wherein the mandrel comprises a bag and an armature; applying a frame mandrel to the mandrel to form a frame for the structure; filling the mandrel and the frame mandrel with media; applying a curable resign to a fiber; applying the fiber over the mandrel and frame mandrel to form the structure; curing the structure; removing the media from the mandrel and frame mandrel; and extracting the mandrel and frame mandrel from the structure.
In accordance with another embodiment of the present invention, preparing further comprises: placing the armature through the bag and conforming the shape of the bag to a desired shape of the structure. This embodiment may also include sealing the bag; placing the armature and the bag in a form tool; and conforming the shape of the bag to the form tool. Further, this implementation may include filling a space between the armature and the bag with air and creating a vacuum between the form tool and the bag to force the bag to conform to the shape of the form tool.
In accordance with another embodiment of the present invention, applying a frame mandrel further comprises applying the frame ply to an exterior of the bag and applying the frame mandrel over the frame ply.
In accordance with another embodiment of the present invention, filling further comprises compacting the media. In this embodiment, compacting may further comprise vibrating the mandrel and frame mandrel to aid compaction.
In accordance with another embodiment of the present invention, applying the fiber comprises winding the fiber over the mandrel and frame mandrel to form the structure. In this embodiment, winding may further include placing a first winding aid on the bag; winding the fiber over the first winding aid, the frame mandrel, and the mandrel to form an inner skin; cutting the inner skin to remove the first winding aids; placing a second winding aid on the inner skin; winding the fiber over the second winding aid and inner skin to form an outer skin; and cutting the outer skin to remove the second winding aids. This embodiment may also include placing a core piece on the inner skin.
In accordance with another embodiment of the present invention, curing further comprises placing a mold around an exterior of the structure; sealing the mold; placing the mold in a heating device; and applying heat to the mold using the heating device. This embodiment may also include creating a vacuum in the mandrel and creating a vacuum in the frame mandrel.
In accordance with another embodiment of the present invention, curing further comprises placing a mold around an exterior of the structure; sealing the mold; placing the mold in an autoclave; and applying pressure to the mold using the autoclave.
In accordance with an embodiment of the present invention, the structure is a fuselage of an aircraft.
In accordance with an embodiment of the present invention, a system for manufacturing a one-piece closed-shape structure using a mandrel comprises: a preparing component configured to prepare the mandrel, wherein the mandrel comprises a bag and an armature; a first applying component configured to apply a frame mandrel to the mandrel to form a frame for the structure; a first filling component configured to fill the mandrel and the frame mandrel with media; a second applying component configured to apply a curable resign to a fiber; a third applying component configured to apply the fiber over the mandrel and frame mandrel to form the structure; a curing component configured to cure the structure; a removing component configured to remove the media from the mandrel and frame mandrel; and an extracting component configured to extract the mandrel and frame mandrel from the structure.
In accordance with an embodiment of the present invention, a computer-implemented method of manufacturing a one-piece closed-shape structure using a mandrel comprises: preparing the mandrel, wherein the mandrel comprises a bag and an armature; applying a frame mandrel to the mandrel to form a frame for the structure; filling the mandrel and the frame mandrel with media; applying a curable resign to a fiber; applying the fiber over the mandrel and frame mandrel to form the structure; curing the structure; removing the media from the mandrel and frame mandrel; and extracting the mandrel and frame mandrel from the structure.
In accordance with another embodiment of the present invention, a system for manufacturing a one-piece closed-shape structure using a mandrel comprises: a preparing means for preparing the mandrel, wherein the mandrel comprises a bag and an armature; an applying means for applying a frame mandrel to the mandrel to form a frame for the structure; a filling means for filling the mandrel and the frame mandrel with media; a first applying means for applying a curable resign to a fiber; a second applying means for applying the fiber over the mandrel and frame mandrel to form the structure; a curing means for curing the structure; a removing means for removing the media from the mandrel and frame mandrel; and an extracting means for extracting the mandrel and frame mandrel from the structure.
In accordance with another embodiment of the present invention, a one-piece closed shape structure comprises: an outer shell formed of a composite material; and a frame formed on an interior portion of the outer shell, the outer shell and frame being co-cured to form the one-piece closed shape structure. In this embodiment, the outer shell may comprise an inner and outer skin. Further, in this embodiment, a core material may be located between the inner and outer skin.
In accordance with another embodiment of the present invention, a one-piece closed shape structure comprises: an outer skin formed of a composite material; an inner skin formed of a composite material; a frame located on an interior portion of the inner skin; and a core material located between the inner and outer skin, wherein the outer skin, inner skin, frame, and core material have been co-cured to form the one-piece closed shape structure.
In accordance with another embodiment of the invention, a one-piece airplane fuselage comprises an outer skin formed of a composite material; an inner skin formed of a composite material; a frame located on an interior portion of the inner skin; and a core material located between the inner and outer skin, wherein the outer skin, inner skin, frame, and core material have been co-cured to form the one-piece airplane fuselage. In this embodiment, the airplane fuselage may further comprise at least one integrally formed flange that has been co-cured with the outer skin, inner skin, frame, and core material. In addition, this airplane fuselage may further comprise at least one integrally formed wing attachment pocket that has been co-cured with the outer skin, inner skin, frame, core material, and flange.
Additional aspects of the invention are disclosed and defined by the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.